diff --git a/hgext3rd/fastverify.py b/hgext3rd/fastverify.py
new file mode 100644
--- /dev/null
+++ b/hgext3rd/fastverify.py
@@ -0,0 +1,57 @@
+# fastverify.py
+#
+# Copyright 2017 Facebook, Inc.
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+"""
+disables parts of hg verify
+
+Manifest verification can be extremely slow on large repos, so this extension
+disables it if ``verify.skipmanifests`` is True.::
+
+    [verify]
+    skipmanifests = true
+"""
+
+from __future__ import absolute_import
+
+from mercurial import (
+    extensions,
+    verify
+)
+from mercurial.i18n import _
+
+testedwith = 'ships-with-fb-hgext'
+
+class fastverifier(verify.verifier):
+    def __init__(self, *args, **kwargs):
+        super(fastverifier, self).__init__(*args, **kwargs)
+
+    def _verifymanifest(self, *args, **kwargs):
+        if self.ui.configbool("verify", "skipmanifests"):
+            self.ui.warn(_("verify.skipmanifests is enabled; skipping "
+                           "verification of manifests\n"))
+            return []
+
+        return super(fastverifier, self)._verifymanifest(*args, **kwargs)
+
+    def _crosscheckfiles(self, *args, **kwargs):
+        if self.ui.configbool("verify", "skipmanifests"):
+            return
+
+        return super(fastverifier, self)._crosscheckfiles(*args, **kwargs)
+
+    def _verifyfiles(self, *args, **kwargs):
+        if self.ui.configbool("verify", "skipmanifests"):
+            return 0, 0
+
+        return super(fastverifier, self)._verifyfiles(*args, **kwargs)
+
+def extsetup(ui):
+    extensions.wrapfunction(verify, 'verify', _verify)
+
+def _verify(orig, repo):
+    with repo.lock():
+        return fastverifier(repo).verify()
diff --git a/tests/test-fastverify.t b/tests/test-fastverify.t
new file mode 100644
--- /dev/null
+++ b/tests/test-fastverify.t
@@ -0,0 +1,25 @@
+  $ cat >> $HGRCPATH << EOF
+  > [extensions]
+  > drawdag=$RUNTESTDIR/drawdag.py
+  > fastverify=$TESTDIR/../hgext3rd/fastverify.py
+  > EOF
+
+Turn manifest verification on and off:
+  $ hg init repo1
+  $ cd repo1
+  $ hg debugdrawdag <<'EOS'
+  > b c
+  > |/
+  > a
+  > EOS
+  $ hg verify
+  checking changesets
+  checking manifests
+  crosschecking files in changesets and manifests
+  checking files
+  3 files, 3 changesets, 3 total revisions
+  $ echo "[verify]" >> $HGRCPATH
+  $ echo "skipmanifests=1" >> $HGRCPATH
+  $ hg verify
+  [verify] disable is set in config; skipping deep verification of repo
+  [1]